Verification of the principle of conservation of momentum

In this experiment a trolley is pushed down a runway which is tilted at an angle so that the speed of the trolley remains constant. It then collides with a second trolley and they travel together to the end of the runway. The velocity of the trolley is measured before and after the collision. If the masses of both trolleys are known the momentum before and after the collision can be calculated. Momentum = (mass)(velocity)

Note: In this simulation the mass of each trolley is 1 kg and the moveable masses are each 0.2 kg.

Procedure:

1. Note the mass on each trolley
2. Press "Push Trolley".
3. Press "Get Tape and Ruler". Drag the marker to a suitable dot on the left hand side of the collision point.
4. Press "Place Mark". Move 5 dots to the left. Press "Place Mark". The distance between the two marks was travelled in 5/50 of a second. Calculate u, the velocity before collision. u = distance / 0.1 m/s
5. By a similar procedure calculate v, the velocity after collision
6. Press "Reset".
7. Press "Move Mass" and repeat steps 1 to 6 until all the masses have been transferred to trolley 2

Analysis:

For each collision calculate the momentum before the collision and the momentum after. The results, subject to small experimental error, should verify the principle of conservation of momentum.

Precautions:

• Ensure that the runway is tilted just enough for the trolley to roll at constant speed
• Ensure that the runway in smooth, free of dust, and does not sag in the middle
• Ignore the first few dots on the tape. These are unreliable and too close together for accurate measurement.
• Place a ruler right on top of the tape when measuring distances to avoid parallax errors